A liquid crystal display panel generally comprises an array substrate, a color film substrate and a liquid crystal layer sandwiched between the array substrate and the color film substrate. Since elements for controlling the display of the liquid crystal layer are mainly formed on the array substrate, the performance of the array substrate has an important influence on the display performance of the liquid crystal display panel. Thin film transistors (TFTs) are widely used in array substrates due to their advantages such as low power consumption, suitable for large scale integration, etc.